This is infeasible, and what does it mean to reject something in a written document?
I don't understand what you're trying to accomplish here: you're arguing against an established convention in a sector of the market which you don't have experience with.
The upside if you're successful is that I don't need to type an additional 'M'.
The downside is that it requires enforcing a blanket standard on an industry, rather than letting it converge over time to an unambiguous standard.
Help the convergence along by objecting to the use of M=1000 wherever you see it. We already have an unambiguous standard (it is the SI system of units and suffixes if you are unsure). People should be using it.
This is unfortunate. $60,000 is $60K (capital K not k) using SI suffixes. Please reject M=1000 today.